Differential Diagnosis for Multiple Tick Bites
Single Most Likely Diagnosis
- Lyme Disease: This is the most common tick-borne illness in the United States, caused by the bacterium Borrelia burgdorferi. It's transmitted to humans through the bite of infected black-legged ticks (Ixodes scapularis). Early symptoms include a distinctive rash, fever, headache, and fatigue.
Other Likely Diagnoses
- Southern Tick-Associated Rash Illness (STARI): Characterized by a rash similar to the one seen in Lyme disease but caused by the bite of the lone star tick (Amblyomma americanum). It does not progress to the later stages of Lyme disease.
- Ehrlichiosis: A bacterial infection caused by Ehrlichia species, transmitted by the bite of an infected tick, typically the lone star tick or black-legged tick. Symptoms include fever, headache, and fatigue.
- Anaplasmosis: Another tick-borne bacterial disease caused by Anaplasma phagocytophilum, with symptoms similar to ehrlichiosis, including fever, headache, and muscle pain.
Do Not Miss Diagnoses
- Rocky Mountain Spotted Fever (RMSF): A potentially fatal disease caused by Rickettsia rickettsii, transmitted by the bite of an infected tick, most commonly the American dog tick (Dermacentor variabilis), Rocky Mountain wood tick (Dermacentor andersoni), or the brown dog tick (Rhipicephalus sanguineus). Early symptoms include fever, headache, and a characteristic rash.
- Tick-Borne Relapsing Fever (TBRF): Caused by various Borrelia species, transmitted by soft ticks (genus Ornithodoros). It's characterized by recurring episodes of fever, headache, and muscle and joint pain.
Rare Diagnoses
- Babesiosis: A parasitic disease caused by infection with Babesia, a group of microscopic parasites that infect red blood cells. It's usually transmitted through a tick bite, most commonly the black-legged tick.
- Powassan Virus Disease: A rare but potentially serious disease caused by a virus transmitted by the bite of an infected tick, primarily the black-legged tick or the groundhog tick (Ixodes cookei). Symptoms can range from mild to severe and include fever, headache, and encephalitis or meningitis in severe cases.
- Tularemia: Also known as rabbit fever, it's caused by the bacterium Francisella tularensis. While it can be transmitted through tick bites, it's more commonly associated with contact with infected animals or contaminated water. Symptoms include fever, chills, and swollen lymph nodes.